For more than a century, commercial laundry industry has confronted a variety of technical challenges. Historically, a typical commercial laundry operation has been expected to handle a variety of fabric types that may be difficult to clean at a typical household. A “dry clean” process was invented in the mid-19th century and became a symbol of the commercial laundry industry. The dry clean process uses chemical agents instead of water and is effective in cleaning wool, silk, fur, and other fabric types which are difficult to clean with water. A first generation of dry cleaning methods generally used petrochemical solvents such as kerosene and even gasoline. Because kerosene and gasoline were found to be excessively flammable and outright dangerous for use in a commercial laundry facility, less flammable petrochemical agents such as a paraffin-derived “Stoddard solvent” were widely used until the 1950's.
The petrochemical solvents used in the first generation of dry cleaning were still frequently susceptible to fire and explosions, and a safer dry-cleaning solvent was need in the industry. Starting in the 1930's, tetrachlomethylene, also known as perchloroethylene or “perc” in short, was discovered to be a very effective and non-flammable dry-cleaning agent. Pere was also gentle to many sensitive garments such as silk and wool. The use of perc in dry cleaning became a defacto industry standard by the mid-20th century and still is a common choice for dry cleaning operations.
However, in the 1990's, tetrachloroethylene was declared to be a carcinogen against humans and a contaminating agent on the Earth's atmosphere. For example, in 1993, the California Air Resources Board devised an airborne toxic control measure to reduce pert emissions from commercial laundry facilities. Many commercial laundry facilities today face strict environmental standard restrictions and even a general phase-out of perc-based dry cleaning machines. Although more eco-friendly chemical agents such as glycol ethers and decamethylcyclopentasiloxane (D5) were devised, increasingly stringent environmental regulations against any chemical dry-cleaning agents and a high cost of operation and equipment have prevented the commercial laundry industry from rapidly adopting such eco-friendly alternatives.
An undesirable alternative to dry cleaning is simply a “wet clean” process, which agitates garments immersed in water with an injection of biodegrable detergents, similar to a modern household washing machine which uses water. Unfortunately, the wet clean process is very undesirable in a commercial laundry operation because only a limited number of fabric types can be treated with a wet-cleaning machine. Furthermore, even fabric types which can be washed with water experience an unacceptable level of shrinkage, wrinkling, and/or damage to garments in a high-volume commercial laundry operation. A laundry facility using water-based wet-cleaning machine inevitably spends an exorbitant amount of time for mitigating shrinkage and wrinkling of garments before a garment press machine can be used. Furthermore, the cost of a water-based wet cleaning machine tends to be even more expensive than a dry cleaning machine.
Therefore, a novel apparatus and a method to provide a cost-effective and environmentally-friendly cleaning of a variety of fabric types with a minimal environmental regulations in a commercial laundry facility is highly desirable.